The determination of the presence and/or amount of analytes in biological fluids, such as blood and saliva, is a useful analytical method. For example, the detection of drugs of abuse in saliva can be useful for determining recent use of the drug by a person (W. Schramm et al, Journal of Analytical Toxicology, 16, 1-9, 1992, "Drugs of Abuse in Saliva: A Review").
Saliva has been used for therapeutic drug monitoring (I.A. Siegel et al, Ann. NY Acad. Sci., 694, 86-90, 1993, "The Role of Saliva in Drug Monitoring"), the measurement of steroids and other endogenous compounds (J. M. Dabbs et al, Clinical Chemistry, 41, 1581-1584, 1995, "Reliability of Salivary Testosterone Measurements") and the measurement of nicotine metabolites (D. L. Colbert and M. R. Holmes, Clinical Chemistry, 40, 843-844, 1994, "Measurement of Salivary Cotinine with Abbott TDx"). Typically, saliva is collected separate from the analytical procedure. In general, the analysis of saliva for analytes is performed with instrumentation in a laboratory and is effected separate from the collection procedure and collection device.
A number of such saliva collection devices have been reported. (See, U.S. Pat. No. 5,334,502, U.S. Pat. No. 5,494,646, U.S. Pat. No. 5,393,496, and U.S. Pat. No. 5,376,337). However, none of these devices collects the saliva and initiates an assay or assays on the saliva simultaneously.
More specifically, U.S. Pat. No. 5,334,502 describes a method for collecting saliva and verifying the quantity of saliva collected. Similarly, U.S. Pat. No. 5,494,646 describes an apparatus for sampling saliva that consists of a sample collector and sample container. Also, U.S. Pat. No. 5,393,496 describes a saliva sampling device including a collection container, a saliva collector and a sample container. Still further, U.S. Pat. No. 5,376,337 describes a saliva sampling device that includes a sample container, a holding reservoir and a filter. Thus, all of such methods and devices provide for the collections of saliva only, and do not allow for both the simple collection of a saliva sample and the simultaneous analysis of analytes in the collected saliva without the need for manipulation of the sample or additional testing steps.
Many different types of assay methods for measuring an analyte in a sample, e.g., a biological fluid are known in the art. Many of such methods are immunological based, i.e., they involve measuring the binding of an antibody or antibody fragment to a complementary ligand, e.g., a drug or other molecule.
Immunoassay methods, in general, are based on the competition between a specific analyte, the concentration of which is to be measured in a sample, and a known amount of tracer, which is generally the analyte or an appropriate analog thereof in labeled form, with the analyte and tracer competing for a limited number of available binding sites on a binder which specifically binds the analyte and tracer. Immunoassays have been used in laboratories for over thirty years.
In some of such procedures, the binders are supported on a solid support such as a porous membrane, whereby the bound and free analytes and tracers of the assay in a liquid matrix, lateral flow by capillary action through the solid support and past the binder(s) and the competitive reaction takes place. In some of such procedures, the tracer is read visually. See e.g., U.S. Pat. No. 4,703,017 and U.S. Pat. No. 5,145,789.
Because of the desire and need for more convenient and less expensive diagnostic methods, there have been efforts in the last twenty years to develop simple tests to allow unskilled persons to perform certain analytical procedures outside of the laboratory. For example, U.S. Pat. No. 5,145,789 describes a device to test urine for human chronic gonadotropin as a means to detect pregnancy. The device is an immunoassay performed on a solid support membrane that provides a visual readout. However, unlike the present device, the specimen to be analyzed is urine rather than saliva and the collection of the urine is performed separate from the analysis.
Also, in the last twelve years there have been developed solid phase immunoassays with visual readouts such as U.S. Pat. No. 4,703,017. U.S. Pat. No. 5,556,789 describes a device for the simultaneous determination of several analytes by solid phase immunoassay with visual readout. U.S. Pat. No. 5,714,341 specifically describes a saliva assay method and device. However, the device requires separate collection of the saliva or other specimen prior to the addition of the specimen to the device. Thus, at least two operations and devices are necessary with these previous methods. First, collection of the saliva specimen with some type of collection device and, second, application of the saliva specimen to the analytical device described in those inventions.
This is disadvantageous as the risk of making errors by untrained users increases when the number of operations and reagents increases. Thus, based on the foregoing, it is clear that it is highly desirable to make available tests for saliva analysis that are simpler than those available now. More specifically, it is clear that a saliva assay device that provides for substantially contemporaneous saliva collection and assay would be highly desirable.